Twist drill sharpeners

ABSTRACT

A drill sharpening and pointing apparatus is provided having a circular grinding disc, means for rotating said disc, a shaft rotatable adjacent said disc on an axis transverse to the disc and carrying a chuck radially spaced from said axis for holding a twist drill and means acting on said chuck means to rotate it through a selected angle less than 360* each time the tool disc rotates 360*.

[ Dec. 10, 1974 1,627,983 5/1927 Maickel........................ 2,147,227 2/1939 Ambler....

Primary Examiner-Harold D. Whitehead Attorney, Agent, or FirmBue1l, Blenko & Ziesenheim [57] ABSTRACT A drill sharpening and pointing apparatus is provided having a circular grinding disc, means for rotating said disc, a shaft rotatable adjacent said disc on an axis transverse to the disc and carrying a chuck radially spaced from said axis for holding a twist drill and means acting on said chuck means to rotate it through a selected angle less than 360 each time the tool disc rotates 360.

1 Claim, 7 Drawing Figures 51/133 ux 51/219 R Schmaltz........................ Schmaltz...........................

Robert B. Henry, Box 188, Wexford, Pa. 15090 Henry, by said Craig Nov. 12, 1970 References Cited UNITED STATES PATENTS Inventors: Joseph C. Craig, Wexford, Pa.;

Assignee:

Appl. No.: 88,807

Int. Field of Search.......................

Unite Stats atet Craig et a1. 1

[ TWIST DRILL SHARPENERS [22] Filed:

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PATENTEUHEII 10 m4 Fig .I.

INVENTIORS Joseph C. Craig 8. Robert B. Henry.

TWIST DRILL SHARPENERS This invention relates to twist drill sharpeners and particularly to an apparatus for sharpening the cutting edges of twist drills.

The problem of sharpening twist drills is an old and well known one. Every twist drill must be originally sharpened before use and after a relatively short time it loses its cutting edge. The grinding of the edge to a satisfactory cutting angle is a relatively complex problem and the machines which have been heretofore successfully used have been complex in structure and expensive. Many of these devices have involved complex planetary gear arrangements which have been expensive and limiting in their usefulness As a result, it has been common practice, particularly in small shops, to simply discard a drill as soon as it becomes dull without any attempt to sharpen it. This is, of course, a very wasteful practice but it is preferred over the problems created by improperly sharpened drills.

We have invented a simple twist drill sharpening apparatus which is relatively inexpensive, yet highly efficient and which will sharpen one or a plurality of twist drills to a proper angle for most effective drilling.

In our invention, we provide a circular grinding disc, means for rotating said disc, a shaft mounted for rotation adjacent said disc on an axis transverse to the axis of the disc, a rotatable chuck means radially spaced from and mounted on said shaft for holding a twist drill to be sharpened with its axis parallel to the axis of said shaft, means acting on said chuck means to rotate said chuck means through a selected angle less than 360 each time the shaft rotates 360 and means for rotating said shaft. Means are provided for moving said shaft and said grinding disc angularly and horizontally whereby the position of the shaft relative to the grinding disc may be adjusted so that the angle of the helical surface on the drill end can be ground to proper relief and proper angularity. The chuck means is mounted preferably in a tool disc mounted on one end of said shaft for rotation therewith adjacent the grinding disc. Preferably the disc is provided with one or more rotatable chucks. lndexing means is provided adjacent the disc for indexing a twist drill in the chuck for proper sharpening. The indexing means preferably folds out of the way when not in use.

In the foregoing general statement, we have set out certain objects, purposes and advantages of our invention. Other objects, purposes and advantages of this invention will be apparent from a consideration of the following description and the accompanying drawings in which:

FIG. 1 is a top plan view of a drill pointer or sharpener according to our invention;

FIG. 2 is a section on the line Il-II of FIG. 1;

FIG. 3 is a side elevational view of the drill pointer of FIG. 1;

FIG. 4 is a fragmentary section on the line IV-IV of FIG. 1;

FIG. 5 is a side elevation of the indexing means of FIG. 1;

FIG. 6 is an end elevation of the indexing means of FIG. I; and

FIG. 7 is a section on the line Vll-Vll of FIG. I.

Referring to the drawings, we have illustrated a table 10 carrying a motor base 11 mounted on a guideway 12 and movable on the guideway by means of screw 13 and nut 14. The base 11 is made up of a generally triangular bottom plate 110 and a like top plate 1111 connected at the apex by a pivot bolt 15. The top plate is pivoted with respect to the bottom plate around bolt 15 and is held in a selected position by means of lock nut 16 and bolt 17 in a slot 18in the top plate. A motor 19 is fixed to top plate 11b and carries a grinding disc 20 on its shaft 21.

A longitudinal shaft is mounted in bearings 31 and 32 in housing 33 mounted on guideways 34 on table 10. The housing 33 is moved on the guideways 34 by screw 35 and nut 36 through miter gear 37 and handwheel 38.

A tool disc 40 is mounted on one end of shaft 30 ad- 15 jacent grinding disc 20 and a drive wheel 41 is provided on the opposite end for rotating the shaft 30 and disc 40. The tool disc 40 is provided with one or more chucks 42 rotatably mounted in the disc 40. Each chuck 42 is adapted to receive and hold a drill 43 to be sharpened. Chuck 42 is provided with an annular ring of gear teeth 44 which engage a gear segment 45 on housing 33 to rotate the chuck through a desired segment of a circle on each rotation of shaft 30. This rotation is preferably through an angle of for usual drill bits so that each of the two cutting edges is alternately brought in contact with the grinding disc. A spring loaded plunger 46 in disc 40 engages depressions 47 in the chuck 42 at 180 spacings to hold the chuck after each such rotation.

Indexing member 50 is mounted on table 10 to pivot about shaft 51 from a point adjacent the tool disc 40 to a reclining position on the table 10.

The operation of the drill sharpening apparatus is as follows: A drill 43 to be sharpened is placed in chuck 42. Indexing member 50 is rotated to its vertical position and the tip of drill 43 is indexed in depression 52 in indexing member 50 and chuck 42 is locked to hold the drill. The indexing member is then dropped to its reclining position. The motor 19 is actuated to rotate the grinding disc 20. Hand drive wheel 41 is rotated to rotate the tool disc 40. This carries the drill tip against the grinding disc and moves the cutting edge along the disc. After the drill tip leaves the grinding disc, the gear segment 45 engages gear teeth 44 on the chuck to release plunger 46 from one detent depression 47 and to rotate the chuck 180 and engage plunger 46 in the next detent depression 47 so that on the next rotation of tool disc 40 the other cutting edge of the drill is brought against the grinding disc. Thus both cutting edges are ground equally. This is done for each chuck on the tool disc so that a plurality of drills can be ground. The tool disc is advanced toward the grinding disc as desired by rotation of hand wheel 38. The angle of the cutting edge is adjusted by rotation of the motor base top plate 11b.

In the foregoing specification, we have set out certain preferred embodiments of our invention. However, it will be understood that this invention may be otherwise embodied within the scope of the following claims.

We claim:

1. A drill sharpening and pointing apparatus comprising a circular grinding disc, means for rotating said disc, a shaft mounted for rotation adjacent said grinding disc on an axis transverse to the axis of said grinding disc, a rotatable chuck means mounted on and radially spaced from said shaft for holding a twist drill for sharpening with the axis of said drill parallel to the axis of said shaft, said chuck means being mounted for rotation in a tool disc mounted on one end of said shaft for rotation with said shaft, indexing means adjacent the tool disc for indexing a twist drill in the chuck for proper sharpening, said index means including a post movable between a horizontal and vertical position, 

1. A drill sharpening and pointing apparatus comprising a circular grinding disc, means for rotating said disc, a shaft mounted for rotation adjacent said grinding disc on an axis transverse to the axis of said grinding disc, a rotatable chuck means mounted on and radially spaced from said shaft for holding a twist drill for sharpening with the axis of said drill parallel to the axis of said shaft, said chuck means being mounted for rotation in a tool disc mounted on one end of said shaft for rotation with said shaft, indexing means adjacent the tool disc for indexing a twist drill in the chuck for proper sharPening, said index means including a post movable between a horizontal and vertical position, said post being held by a stop in the vertical position and means acting on said chuck means to rotate said chuck means through a selected angle less than 360* each time the tool disc rotates 360* and means for rotating said shaft. 